1. Field of the Invention
The field of the present invention is an optical device for the visualization of a three-dimensional virtual image in superposition with a real object, especially for surgical applications.
2. Description of the Related Art
In the state of the art, processes are known for the construction of three-dimensional synthesized images from images obtained with imaging means such as a scanner, a tomograph or any other equivalent device. These images are then used for guiding surgical instruments.
As an example, German patent DE 3717871 describes an optical representation process and device for surgical interventions.
This process is intended for the reproducible optical representation of an intervention to be implemented with the aid of a surgical instrument. In this process the tomographic data for the part of the body in which the surgical intervention will be implemented are entered into the data memory of a data processing system. The data relative to the position of the field of intervention are determined from the tomographic data. In the process according to this prior document, the surgical instrument is fixed on a freely movable three-dimensional support, and the data relative to the position of the surgical instrument are determined by means of a coordinate measurement device and transmitted to the data processing system, which establishes a relation between the data relative to the position of the surgical instrument and the data relative to the position of the field of intervention, and with which the surgical instrument is oriented to the field of intervention by means of this relation. The process involves the following steps:
at least three measurement points accessible from the exterior are determined or established as reference points on the body part, PA1 tomograms including the measurement points are implemented on the body part and entered into the data memory, PA1 the position in space of the measurement points is determined by the coordinate measurement device; PA1 the measured data are entered into the data memory, PA1 the data processing system establishes a relation between the image data of the measurement points contained in the tomograms and the data determined by the coordinate measurement device from the measurement points, PA1 the coordinate measurement device continuously detects the position in space of the freely movable three-dimensional surgical instrument, and the position data are transmitted to the data processing system, PA1 the data processing system superposes the data relative to the position of the surgical instrument to the tomographic image data, and the data processing system produces superposition images on an output device, particularly a visualization screen, in which the tomographic image contents and the respective positions of the surgical instrument are superposed.
The processes according to the state of the art, however, do not allow satisfactory exploitation of the three-dimensional images under the usual operating conditions. The visualization devices of the prior art impose a specific operating technique, which is not very compatible with the usual movements of the visualization operator on an independent screen or on a helmet.